Method of implanting a sleeve in a lumen

ABSTRACT

A prosthesis for use in preventing restenosis after angioplasty is formed of plastic or sheet metal. It is expandable and contractable for placement. The prosthesis can be inserted while in a collapsed position, then expanded and locked in the larger diameter. Spring force can be provided by the material itself or metal springs can be imbedded within the walls of the prosthesis. Preferably, the walls have holes therethrough to promote tissue growth; and, in one embodiment the holes are in the form of slots so that the prosthesis is segmented and can bend longitudinally.

[0001] There has been considerable use of balloon angioplasty due tostenosis in arteries having atherosclerotic plaque and the like in aneffort to enlarge the lumen and to provide adequate blood flow. Whilesuch angioplasty has been successful, it has been found that in manycases re-stenosis requires that the procedure be repeated.

[0002] More recently, there have been efforts at following the balloonangioplasty with placement of a stent, the stent being in the nature ofa sleeve that will mechanically maintain some minimum lumen diameter.

[0003] It will be obvious that, in order to place a stent utilizing theballoon angioplasty technology, the stent must necessarily have asufficiently small external diameter to be moved into the desired areaby some means such as a catheter, then to be expanded, both to be heldin place by the arterial elasticity and to provide the minimum lumendiameter. Prior stents have generally taken the form of wire mesh thatis collapsed for placement into the artery, then expanded, either bymeans of a balloon or by its own elasticity. The stent is generally heldin place simply by the arterial elasticity in the first instance, and ithas been found that epithelialization takes place throughout the stentso that the entire stent becomes effectively embedded in the vesselwall.

[0004] The prior art stents, being woven stainless steel wire or thelike tend not to be very flexible longitudinally so that their primaryuse is in straight portions of vessels. Also, inflation of the balloonis required to expand the wire to its desired size in some cases, whileother wire mesh stents tend to take a particular size, and must be heldby a sleeve or the like during placement.

SUMMARY OF THE INVENTION

[0005] This invention relates generally to protheses, and is moreparticularly concerned with a prosthesis in the form of a stent to beplaced in a vessel for mechanically maintaining an opening.

[0006] This invention provides a stent for maintaining a minimum openingthrough an artery or the like, the stent being in the form of a sleevehaving a discontinuity so the sleeve has a collapsed position to beassumed during placement of the stent, and an expanded position for usein its final location for maintaining the desired opening. In oneembodiment of the invention, the stent may be carried by one catheterwhile a second coaxial catheter in the nature of a conventional ballooncatheter is carried therein. This arrangement allows use of the ballooncatheter to provide a mechanical opening in the vessel, then to allowthe stent to be slipped into place over the balloon. The balloon canthen be used to manipulate the stent for any necessary opening of thestent and disengagement of the stent from the coaxial catheter. It isalso contemplated that the stent of the present invention can be carriedby a single, generally conventional balloon catheter.

[0007] The stent of the present invention may selectively be biasedtowards a closed position and lockable in an open position, or biased inan open position and lockable in a closed position. In the former case,the stent will be put into place in its collapsed condition, thenforcibly expanded by a balloon or the like to the desired lockedcondition. In the latter case, the stent may be held by a pin or thelike in its collapsed condition, and the pin removed to allow the stentto assume its open position.

[0008] The stent of the present invention may be made from any numerousmaterials, including metal or the like, and also including variousplastic materials. The plastic materials may be simply homogenous moldedplastics, or may comprise a plastic covering over a knit or woven mesh.The knit or woven mesh may, in turn, be metal or plastic. The precisematerial can be selected to achieve the desired features of the stent.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] These and other features and advantages of the present inventionwill become apparent from consideration of the following specificationwhen taken in conjunction with the accompanying drawings in which:

[0010]FIG. 1 is a perspective view showing one form of stent made inaccordance with the present invention and carried by a coaxial catheter;

[0011]FIG. 2 is an enlarged cross-sectional view taken substantiallyalong the line 2-2 in FIG. 1;

[0012]FIG. 3 is a cross-sectional view of a slightly modified form ofstent shown in its open and locked position;

[0013]FIG. 4 is a fragmentary view showing the stent of FIG. 3 afterexpansion beyond its maximum, open position;

[0014]FIG. 5 is a fragmentary perspective view, partially incross-section, showing one form of material for use in constructing thestents of the present invention;

[0015]FIG. 6 is an elevational view showing another modified form ofstent made in accordance with the present invention, the stent beingcarried on a catheter;

[0016]FIG. 7 is a cross-sectional view taken substantially along theline 7-7 in FIG. 6;

[0017]FIG. 8 is a fragmentary view showing the stent of FIG. 7 afterexpansion;

[0018]FIG. 9 is a top plan view of another modified form of stent madein accordance with the present invention, the stent being shown withoutthe carrying catheter;

[0019]FIG. 10 is a bottom plan view of the device shown in FIG. 9;

[0020]FIG. 11 is an enlarged cross-sectional view taken substantiallyalong the line 1111 in FIG. 9; and

[0021]FIG. 12 is a view similar to FIG. 11 but showing the stent in itsexpanded condition.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Referring now more particularly to the drawings, and thoseembodiments of the invention here presented by way of illustration, FIG.1 shows a stent generally indicated at 15, the stent 15 being carried bya catheter 16. The catheter 16 is one of two coaxial catheters, theother catheter 18 being a generally conventional balloon catheter havingthe balloon 19 at its distal end.

[0023] It will be understood by those skilled in the art that, inconventional, balloon angioplasty, a catheter such as the catheter 18 isthreaded through the arterial system to place the balloon at thelocation of the stenosis. The balloon 19 is then inflated to urge thearterial wall outwardly and open the lumen in the artery. This sametechnique will be utilized with the arrangement shown in FIG. 1 of thedrawings, the balloon 19 acting to perform the angioplasty; however,after the vessel is sufficiently open by means of the balloon 19, thecoaxial catheter 16 will be manipulated to urge the stent 15 in placeover the balloon 19. After the stent 15 is over the balloon 19, theballoon 19 will be inflated to urge the stent outwardly to its openedcondition.

[0024] Referring to FIG. 2 of the drawings, it will be seen that thestent 15 includes a wall 20, the wall 20 having sufficient memory thatthe stent as a whole tends to maintain its collapsed condition. One endof the wall 20 is provided with a hook 21 for engagement with one of aplurality of complementary hook means 22. The hook 21 will necessarilybe biased outwardly sufficiently that, as the hook 21 is urged past theplurality of hook means 22, the hook 21 will engage each of the hooks22. Because of this arrangement, when the balloon 19 is not furtherinflated, the hook 21 will remain engaged with one of the hooks 22 toprevent collapse of the stent 15.

[0025] It will also be noticed that the stent 15 contains a plurality ofgenerally circumferential ribs 24. It is contemplated that the ribs 24will engage the arterial walls sufficiently to prevent inadvertentmovement of the stent after placement and removal of the catheter 16. Aswill be discussed hereinafter, the stent 15 may also contain a pluralityof openings to allow tissue to grow therethrough and further hold thestent 15 in place.

[0026] Looking now at FIGS. 3 and 4 of the drawings, it will be seenthat the stent 25 is a slightly modified form of the stent 15. The stent25 includes the wall 26 which will be biased towards collapse as is thewall 20 of the stent 15. Once the stent 25 is urged to its expandedcondition, the interlocking hook means 28 will become engaged as shownin FIG. 3 to prevent collapse of the stent 25 and maintain the stent inits maximum, open condition.

[0027] It will be understood that there may be times when the stent isimproperly placed, or for other reasons must be removed. With the stent25, the ends 29 and 30 of the wall 26 are so biased that, when the stent25 is expanded so far that the ends 29 and 30 are released fromengagement, the end 29 will move inwardly and the end 30 will moveoutwardly. On subsequent release of the stent 25, the walls 29 and 30have exchanged places so that the hook means 28 cannot now engage. As aresult, the stent 25 will collapse to its minimum external diameter.

[0028] Though many different materials may be utilized in forming thestents of the present invention, one form of material is illustrated inFIG. 5 of the drawings. In FIG. 5 there is a woven network indicated at31. This woven network may be metal such as stainless steel or the like,or may be a knit or woven plastic material such as polyester filaments.If the network 31 is made of metal, the intersections can be sonicallywelded or otherwise heat sealed to one another.

[0029] Following provision of the network 31, the network 31 is coveredby a plastic material indicated at 32. The material 32 can again be anyof numerous materials, so long as the material is implantable.Nevertheless, numerous plastic materials including polyethylene,polyester, polytetraflouroethylene and others can be utilized.

[0030] As illustrated in FIG. 5, the network 32 is simply coated withthe material 32 so that openings 34 are distributed throughout thematerial. While the openings 34 are not necessarily so uniformlydistributed, it will be understood that the use of a plurality ofopenings 34 promotes epithelialization to promote incorporation of thestent into the vessel wall.

[0031] Turning now to FIG. 6 of the drawings, there is a stent indicatedat 35 carried at the end of a catheter 36. The catheter 36 includes aballoon 38 as is known in the art.

[0032] While the above described stents have been biased inwardly andhave been forced outwardly, the stent 35 is biased outwardly and isforced inwardly and retained by means of a pin 39. For a fullunderstanding of the stent 35, attention is directed to FIGS. 6, 7 and 8of the drawings which show both plan view and cross-sectional views ofthe stent 35.

[0033] The stent 35 is here shown as having a generally smooth wall 40having a plurality of openings 43 in accordance with the foregoingdiscussion. The wall 40 is biased outwardly towards its maximumdiameter; however, for placement by means of the catheter 36, the stent35 is urged inwardly to its minimum diameter, and the stent is providedwith a first pair of lugs 41 carried on the end 42 of the wall 40, andsecond pair of lugs 44 carried generally towards the opposite end 45 ofthe wall 40. When the wall 40 is urged inwardly to collapse the stent35, appropriate openings in the lugs 41 and 44 are aligned, and the pin39 is placed therethrough to hold the stent 35 in its collapsedposition.

[0034] As is shown in FIG. 6 of the drawings, it is contemplated thatthe pin 39 will be in the form of a wire that extends along the catheter36, contained within a channel 46. With this arrangement, the pin 39will extend to the lug 44 at the distal end of the stent 35, and it willbe understood that the distal end lug 44 may have a hole that does notextend completely through the lug in order to cover the end of the pin39. The pin 39 then extends the full length of the stent 35 and into thechannel 46. While not here illustrated, it will be understood that thepin 39 extends completely along the length of the catheter 36 so the pin39 can be manipulated externally of the body so that, at the appropriatemoment, the pin 39 can be removed from the lugs 41 and 44 and allow thestent 35 to expand.

[0035] As here shown, when the stent 35 expands, the ends 42 and 45 willremain overlapped to some extent. If desired, interlocking grooves 48and 49 can be provided so the stent 35 has a relatively fixed expandeddiameter.

[0036] Attention is next directed to FIGS. 9-12 of the drawings whichshow another modified form of stent. The stent 50 is similar to thestent 35 in that it is biased outwardly and is forcibly held inward by apin; however, the stent 50 is considerably different from the stent 35in that the stent 50 is of a somewhat segmented construction to allowlongitudinal flexibility.

[0037] In the top plan view shown in FIG. 9 of the drawings, it will beseen that the stent 50 includes a plurality of segments 51, each segment51 having a lug 52 thereon for receipt of a pin 54. The segments 51 areinterspersed with segments 56 on the opposite side of the pin 54, thesegments 56 having lugs 58 thereon. As is better shown in FIG. 10 of thedrawings, there is a generally continuous spine 59 extending along thebottom of the stent 50 and interconnecting all of the segments 51 and56. Because of this construction, it will be seen that the stent 50 willbe readily bendable along its longitudinal axis, the bending beingresisted only by the relatively narrow spine 59. Furthermore, it will beunderstood that the individual segments 51 and 56 can be made muchshorter to provide for tighter radii, or relatively long in the eventthe stent is not intended to be very flexible.

[0038] Though the stent 50 in FIGS. 9-12 of the drawings is not shown inconjunction with a catheter, it will be understood by those skilled inthe art that the stent will be put into place using an arrangement suchas that shown in FIG. 6 of the drawings. The catheter 36 and wirechannel 46 would be the same, the specific stent being the onlydifference.

[0039]FIG. 11 of the drawings shows the cross-sectional shape of thestent 50 while the stent is held in its closed, or collapsed, conditionby the pin 54. When the pin 54 is removed, the stent 50 will expand tothe condition shown in FIG. 12 of the drawings. It will of course berecognized that a balloon, such as the balloon 38, may be utilized toassist in urging the walls of the stent outwardly to the desiredposition.

[0040] The material from which the stent 50 is made may be any of thenumerous materials previously mentioned, including the material shown inFIG. 5 of the drawings. Because the stent 50 is made up of a pluralityof individual segments 51 and 56, there is no particular need foradditional openings in the wall of the stent, the spaces between thesegments providing adequate openings for initial fluid drainage andsubsequent epithelialization.

[0041] Simply by way of example, FIGS. 10 and 12 illustrate theinclusion of a filament 60 in the wall of the stent. The purpose of thefilament 60 is to show that the stent 50 can be made of a plasticmaterial having sufficient memory to be urged to the open condition asshown in FIG. 12; or, the stent 50 can be made of a relatively flaccidfabric or the like having spring filaments 60 embedded therein forurging the stent 50 to its open position. Also, the stent 50 can be madeentirely of metal, including well known alloys of platinum and gold, orchromium and cobalt.

[0042] From the foregoing discussion it will be understood that thepresent invention provides an arterial stent and a method for placingthe stent for preventing re-stenosis following angioplasty or othermechanical opening of the lumen in an artery. While several specificdesigns and materials have been disclosed, those skilled in the art willrecognize that the materials must be implantable, and all portions ofthe stent must be sufficiently smooth to prevent trauma duringplacement. Further, all corners and the like should be well rounded topromote epithelialization without subsequent trauma due to the presenceof sharp edges during natural body motions.

[0043] It will of course be understood by those skilled in the art thatthe particular embodiments of the invention here presented are by way ofillustration only, and are meant to be in no way restrictive; therefore,numerous changes and modifications may be made, and the full use ofequivalents resorted to, without departing from the spirit or scope ofthe invention as outlined in the appended claims.

1. A method of maintaining a minimum opening in a lumen of an animal orhuman body comprising: providing a sleeve that is biased toward aradially collapsed position, providing a catheter, mounting the sleevein its radially collapsed position on the catheter, inserting thecatheter with the collapsed sleeve mounted thereon into a lumen of ananimal body, carrying the sleeve in its collapsed position with thecatheter along the length of the lumen to a position in the lumen wherethe minimum opening in the lumen is to be established, radiallyexpanding the catheter inside the sleeve, radially expanding the sleevein response to the radial expansion of the catheter in the position ofthe lumen where the minimum opening in the lumen is to be established,radially expanding the lumen in response to the radial expansion of thesleeve, maintaining the sleeve in its radially expanded position,collapsing the catheter inside the sleeve, and withdrawing the catheterfrom the sleeve and from the lumen.
 2. The method of claim 1, whereinthe step of providing a catheter comprises providing a catheter with aballoon at its distal end, and the step of radially expanding thecatheter comprises inflating the balloon.
 3. The method of claim 1,wherein the sleeve when in its collapsed position defines a longitudinalgap and the sleeve is in the form of a coil, and wherein the step ofradially expanding the sleeve comprises transforming the sleeve from itscoiled position into a cylindrical position.
 4. The method of claim 3,wherein the step of radially expanding the sleeve comprises expandingthen sleeve to a predetermined circumference.
 5. The method of claim 3,wherein the sleeve has ends adjacent its gap, and the step ofmaintaining the sleeve in its radially expanded position compriseslocking the ends of the sleeve together.
 6. The method of claim 5,wherein the step of locking the ends of the sleeve together comprisesplacing the ends of the sleeve in overlying relationship, and lockingthe ends of the sleeve together in overlying relationship.
 7. The methodof claim 5, wherein the sleeve has connectors on at least one of itsends, and wherein the step of locking the ends of the sleeve togethercomprises locking the connectors to the ends to establish the sleeve ina position of a predetermined circumference.
 8. The method of claim 1,wherein the step of providing a sleeve comprises providing a sleeve witha network of openings formed therein, and further including the step ofcovering the openings with epithelial tissue from the lumen.
 9. Themethod of claim 1, wherein the step of providing a sleeve comprisesproviding a sleeve having a network, and a covering applied to thenetwork, with the network and covering defining a plurality of openings,and further including the step of forming epithelial tissue about theopenings.
 10. The method of claim 1, and further including the step ofpreventing re-stenosis in the lumen about the sleeve.
 11. A method ofmaintaining a minimum opening in a lumen of an animal or human body,comprising: providing a sleeve having a network defining openings, anetwork, and a coating applied to the network, with said sleeve biasedtoward a radially collapsed position, carrying the sleeve in itscollapsed position along the length of a lumen to a position in thelumen where the minimum opening in the lumen is to be established,radially expanding the sleeve, radially expanding the lumen in responseto the expansion of the sleeve, locking the sleeve in its radiallyexpanded position, and covering the openings with epithelial tissue. 12.The method of claim 11, wherein the step of locking the sleeve in itsradially expanded position comprises locking the sleeve to itself inresponse to radially expanding the sleeve.
 13. The method of claim 11,wherein the step of providing a sleeve having a network definingopenings in the sleeve includes providing a covering applied to thenetwork, with the network and covering defining a plurality of openings,and further including the step of forming epithelial tissue about theopenings.
 14. The method of claim 11, wherein the step of providing asleeve comprises providing a sleeve that defines a longitudinal gap withsaid sleeve formed in a coil and with first and second ends adjacent thegap, and a hook means on the first end facing the second end, and firstand second hook means on the second end facing the first end, andwherein the step of locking the sleeve comprises engaging the hook meansof said first end with the first hook means of the second end to expandthe sleeve to a first diameter, and engaging the hook means of the firstend with the second hook means of the second end to expand the sleevetop a second diameter.
 15. The method of claim 14, and further includingthe step of opening the sleeve by expanding the sleeve so that its endsmove beyond each other and collapsing the sleeve with the hook means ofeach sleeve end facing away from the opposite sleeve end.
 16. The methodof claim 11, and further including the step of retarding movement of thesleeve along the length of the lumen in response to expanding thesleeve.
 17. The method of claim 11, wherein the step of providing asleeve comprises providing a sleeve having circumferential ribs, and thestep of expanding the sleeve comprises expanding the circumferentialribs into contact with the lumen, and retarding movement of the sleevealong the length of the lumen with engagement of the ribs with thelumen.
 18. The method of claim 11, wherein the step of providing asleeve with a network comprises providing a sleeve with a woven networkwith intersections connected together.
 19. The method of claim 18,wherein the step of providing a sleeve with a network comprisesproviding a sleeve with a woven network of steel, and a covering formedabout the steel, and the step of radially expanding the sleeve comprisesengaging the lumen with the covering.
 20. The method of claim 19,wherein the covering defines openings therein, and promotingepithelialization of the lumen about the sleeve, and promotingincorporation of the sleeve into the lumen.
 21. A method of preventionof re-stenosis, comprising: providing a sleeve formed in by a network ofmaterial and a coating applied to the network, leaving openingsthroughout the sleeve, inserting a sleeve in a lumen in an area wherethe prevention of re-stenosis is desired, expanding the sleeve in thelumen and expanding the lumen in response to the expansion of thesleeve, as the sleeve expands contacting the lumen with the coating,promoting epithelialization of the lumen about the coating.